1. Field of the Invention
The present invention relates to a process for production of liquid polymers having active terminal groups. More particularly, the present invention relates to a process for production of chloroprene-based liquid polymers having active terminal groups substantially on both ends thereof by radical-telomerizing chloroprene alone or in combination with monomers copolymerizable with chloroprene in the presence of a xanthogen disulfide compound in an organic solvent.
2. Description of the Prior Art
Hitherto, research has been conducted on liquid polymers which can be easily cured at desired temperatures to form an insoluble elastomer having elasticity due to crosslinking reactions and further, which can maintain its liquidity for a long period of time. Thus, various processes have been proposed for production of chloroprene-based liquid polymers satisfying the above-mentioned requirements. Of these polymers, a liquid polymer which is produced by subjecting chloroprene to an aqueous emulsion polymerization in the presence of dialkyl xanthogen disulfide, for example, as disclosed in British Pat. Nos. 905,971 and 963,075, satisfies these requirements relatively well. This process, however, has defects in the separation of the polymer from the emulsion, the qualities of the polymer product, the economy, and the like. That is, the following defects have been confirmed to exist.
1. Defects in polymer separation
The drum drying method, for example, as in U.S. Pat. No. 2,914,497, is generally employed in the separation of a liquid rubber from a synthetic rubber latex. In order to substantially completely remove the aqueous medium of the rubber latex, the rubber latex must be treated on a drum maintained at high temperatures of from about 120.degree. to 150.degree. C. Thus, the qualities of the polymer product such as the physical properties, color, odor, and the like are inevitably degraded by the deterioration of the rubber itself during drying, the thermal decomposition of residual emulsifying agents and auxiliary emulsifying agents, and the like.
2. Defects in the qualities of the polymer product
Since the emulsifying agents and auxiliary emulsifying agents necessarily remain in the polymer product, the qualities of the polymer product, particularly in odor, color, transparency and the like are reduced. Of the physical properties, elongation is particularly small.
3. Economic defects
In producing a polymer which is liquid at room temperature, the xanthogen disulfide compound as a chain transfer agent must be added in a large amount as compared with solution polymerization.